The present invention relates to an electromagnetic shielding material for absorbing electromagnetic energy.
The electromagnetic shielding material is used, for example, as a casing material of an electronic device to prevent the leakage of undesired electromagnetic waves generated in the noise source.
Conventionally, a composite material has been used as the electromagnetic shielding material, which has been prepared by dispersing metal or conductive material is dispersed in a resin. In another case, the shielding material was manufactured by providing conductive coating to the surface of a plastic material by using zinc flame spraying or painting of conductive material.
The conventional shielding material prevents the transmission of the electromagnetic waves by reflecting part of them and absorbing part of them using ohmic loss.
Accordingly, the conventional shielding material has the disadvantage that undesired electromagnetic waves are confined in the electronic device and their intensities increase in the same. This phenomenon leads to an interference between each of the circuits of the electronic device, or to leakage of noise from the electronic device through a connector or air hole where shielding is insufficient.
It is an object of the present invention to overcome the disadvantages of the prior art by providing a new and improved electromagnetic shielding material.
It is another object of the present invention to provide an electromagnetic shielding material with high electromagnetic energy absorbing capability.
According to an aspect of the present invention, there is provided an electromagnetic shielding material having electromagnetic absorbing property comprising a composition consisting of Mn-Zn ferrite powders, conductive carbon powders and organic high molecular weight compounds; the content of the Mn-Zn ferrite powders being in the range between 30 and 70 vol%; and the composition having volume resistivity in the range between 10.sup.2 and 10.sup.-1 ohm.multidot.cm.